Calibre for iPad?

I’ve been a long time Calibre user, but have recently had to switch from a laptop to an iPad. The only problem with that is that I can’t seem to find a way to continue to use Calibre. Is that possible? Or is there anything similar to Calibre that is available for iPad? I need something that will convert ePub to mobi, without too much hassle, and allow me to organise my ebook library.

Thanks so much for your help!